Sound-locating device



June 16, 1925. 1,541,836 V A. MC NAB SOUND LOGATING DEVICE Filed Jan. 2i, 1929 ldateuted .lune ld, wml..

r oir-ricaw atmrannna nenne, or entnenron'r, counncricnr.

.application led January 21,1920. Serial No. 352,981.

\ To all whom it may concern.

` cal research inasmuch as it is extremely yinstrument in its complete form;

sensitive and may be advantageously employed in lieu of the stethoscopes now commonly used.

' The structure is illustrated in the annexed drawings, wherein,-

llllig. 1 is a diagrammatic elevation of the Fig. 2 a longitudinal sectional View, with parts in elevation,. of the hand piece carrying the make and .break device adapted to be brought into action yor functioning relation by a pressure producing element which v minal 16 mounted in head 13; The body 14 latter is forced against or held in Contact with the machine (or other body) from which tliesound to be located eraanates;

ig. 3 an enlarged sectional view thereof; an Y, i

lllig. 4 a sectional view showing a slight modification or adaptation of the structure. Referring first to Figs. 1 to 3, 1 denotes a suitable box or case in which .is lined two 'spring terminals 2 and 3 between which is placed a dry cell or battery. 4. fin induction coil is also located within the box, the secondary winding whereof is connected by leads 6 and 7 with the ear piece 8 of any approvedtype of head set, indicated generally by 9. A leadl() entends from terminal 2 to one terminal-of the primary winding of the induction coil anda .lead 11 lextends from the opposite terminal of the primary winding to a socket terminal 12,mounjted in the 'head 13 of the hand piece, the main body whereof' is designated by 14. IA lead 15, 'extends from the terminal 3 to' a seco-nd socket teris preferably formed of a suitable dielectric material as gutta-perclia and carries a pair of metal pins or posts 1t? and 18 preferablj7 split at their outer ends to produce a close contact with the wall.' of the respective sockets l2 and 16 intovwhicli the pins extend. Pin 17 is connected through a wire 19 with a metallic sleeve or bushing 2() 60 lixedlysecured in the forward portion of a socket or recess 21 formed in the rear portion ofthe body 14. Said sleeve .is internally threaded and a screw 22 is mounted therein,

the head of the screw being housed within the recess 21, while its forward end-extends into a bore which passes longitudinally through the body member 14.

Located within the bore in advance of and in contact with the screw is a disk 23 formedm of 'carbon oi platinum, said disk in turn f bearing against a body of carbon 24, said body being somewhat loosely confined between disk 23 and a similar disk 25.

tending forwardly from the latter is a` plunger pin 26; a spring 27 is interposed bevtween said pin and a second pin or rod 28. ln other words, the pins 26 and 28 and the intermediate spring form a yielding pressure device which'exerts a compressive force 80 upon'the variable resistance element 24.

'lhe outer end of the body 14 is reduced in diameter somewhat and a cap piece 29 is screwed thereon, said cap confining a felt nose piece or button 3Q which forms the guide or support for a linger 81, said linger carrying at its inner end a head 32 which bears against the forward end of rod 28. The finger 31 is designed to be pressed againstthe body from .which tlie'sound lto be located enianates, as for instance, a cylinder head 33, Fig. 1, and to transmit the sound waves or vibrations through the rods 26, 28 and s ring. 27 to the variable resistance element l2 Saidrods are housed within and in contact with a metallic sleeve or bushing 34 secured withinthe body 14 and said sleeve is connected "with the pin 18 through a wire 35 embedded in the body. To maintain the screw 22, Awhen vonce brought to such position that the variable resistance element will be held under the requisite degree of compression when the linger 31 is forced inwardly, will be secured in place as by pouring a body of sealing wax 36 in the cavity 21,@the wan, when it becomes hard, preventing the screw from turning in either direction. The instrument may be readily ad'- 4justed; Placing the linger 31 against a body parts intheir pro-per working relation, the

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from which a known sound emanates, and with the head piece 9 in place, one may readily determine Whether the element is under the proper degree of compression. By removing the cap 13 access is had to the screw which is turned in or out and the cap replaced reestablishing the circuit connections. vWhen the screw is finally brought to its proper position it is 'secured in any suitable vvay, as by Wax; as above indicated, and the cap replaced.

n F ig. 4 a modification of the invention is illustrated, certain features of which may be incorporated in the form just described.

Under this arrangement it Will be noted that the screu7 22 extends outwardly through .an opening formed in the head 18 and is provided With a milled head 22a by which it may be adjusted. This permits manual adjustment of the screw, if for any reason a greater or less pressure is desired upon the variable resistance. So also instead of employing a straightrounded finger the finger designated by 3la carries at its outer end a .cupped shaped element, as 37, thereby adapting the instrument to stethoscopic purposes. W'hen so employed it may be found necessary to vary the resistance and by the utilization of the milled head 22a this may be readily effected. .v

From the foregoing it is thought that the operation and utilization of the instrument will be readily appreciated. The. various parts which are not permanently attached to the box may be readily housed therein and 3 thus a simple portable apparatus provided.

lVhat is claimed is: l. ln a microphone for use in sound locat-l ing devices the combination of a body; a rcsistance mounted therein land adapted to 0 e included in a circuit With the primary lwindings of a coil; a plunger extending for-l Avariable resistance element mounted in the body and adapted to be included in the circuit of t-he primary windings of a coil; a yielding pressure device located in the body and exerting a compressive force uponthe variable resistance; a soft nose piece carried by the body in line with the yielding pressure device; and a finger extending through said nose piece being guided and supported thereby, said finger at its inner end contacting u'pon the yielding pressure device.

ln testimony whereof l have signedv my G5 name to this specification.

ALEXANDER MCNAB. 

